Cryonic suspension, sometimes called cryonic freeze is a state of low-temperature organic preservation and metabolic suspension, the intent being to later revive the subject, alive and well.
During the 22nd Century, early Earth spaceships on long voyages - such as the USS Copernicus - used Cryonic freezers to suspend the crew during extended flights, that were sometimes years in duration. This method would quickly become obsolete following first contact with the Centauri Republic in 2156 and the purchase of jump drive technology, that allowed lightyears of distance to be crossed via hyperspace in days rather than decades, or centuries.
Cryonic suspension also has certain medical applications, though mostly as a means of preserving terminally ill or injured patients until a suitable treatment can be found or the patient can be moved to more suitable facilities. Earth Alliance Medlabs are routinely equipped with several banks of cryonic freezer units, though no more than four or five are supposed to be used at any given time and only then when required by a medical emergency until they can be sent back to Earth for treatment.
During the First Shadow War, an race that refused to allow the Shadows to build a base on their world were infected by a nano-virus that would kill all life within 5 years. After 3 desperate years of trying to find a cure on their world and with too few jump capable ships to search off-world, they resorted to placing their entire population, billions of people into Cryonic suspension, hidden deep underground. Meanwhile they left incomplete formulas, promising advanced technology and insight written openly on their abandoned buildings, to lure in visitors from off-world and set up a series of powerful automated machines and probes that would continue the research by capturing and experimenting on any aliens that visited. The cryonic suspension was successful in halting the progress of the virus, however as soon as an individual was unfrozen, the virus would continue where it left off, killing the subject within 2 years. While the others slept, a single caretaker remained awake, running the tests for as long as they were able. By the time the Excalibur visited the world in 2267, Kulan the current caretaker was only the latest with 500 before him having died in their endeavour.
In 2260, elements within Psi Corps handed over one hundred blips in cryonic suspension to the allies of the Shadows. The Telepaths were modified with Cyberweb Implants and were to be used as weapons components in their ships. Before they could be installed however, the shipment was intercepted by the White Star and taken back to Babylon 5. Since the station was only set up to handle a small number of short-term cryonic units, the medical staff had to improvise, which resulted in a mechanical failure in the following year. Following the Battle of Mars, the surviving telepaths were transferred back to Earth, where there were better facilities for studying how to safely remove the implants.
By the mid-25th Century, cryosuspension had become a thriving industry, with several companies such as SleepWorld and Ever-Dream Enterprises offering long-term suspension for a fee. Whole families would often freeze themselves, hoping to see a better future, though as one of EDE's techs pointed out: "the future's always just like the present, only moreso." Early on the service was also used by criminals, trying to escape the statute of limitations which in turn prompted Earthgov to pass the Chrono Fugitive Laws, to prevent suspects escaping justice in the future. In 2261, following a complete metabolic shut down caused by the Energy Transfer Device, Marcus Cole was place in indefinite cryonic suspension at the request of then Commander Susan Ivanova. Three hundred years later, in 2560 Cole was eventually revived after the technology that originally drained him had been sufficiently understood.
- In the commentary for ("Racing the Night"), JMS notes that the consultants at JPL noted that sci-fi writers often confused cryonics (the preservation of living beings through low temperatures) with cryogenics (the study of low temperatures) and so obliged them by correctly using the term in the episode of Crusade.
- Prior to that point the term "cryogenic" had been incorrectly used in a number of episodes; ("The Long Night"), ("Ship of Tears"), ("Epiphanies") and ("The Illusion of Truth"). However, both ("Deathwalker") and ("The Face of the Enemy") featured a correct use of the term "cryonic", as did the graphic at the end of ("Sleeping in Light"), showing Marcus's cryotube display.